Apparatus for fabricating brushes having molded ends

ABSTRACT

A brush molding method and apparatus in which synthetic brush filaments within a mold cavity are held in place by an internally movable plug. The protruding ends of the synthetic brush filaments are heated and melted into a liquid mass in the mold cavity, and a brush handle is then inserted into the mold cavity, closing the mold and pressing the liquid into the desired shape, and at the same time fusing the filaments together to form a base for the brush and sealing the formed base to the handle. To mold a brush without a handle, a movable platen may be substituted for the handle.

United States Patent Bischoff 1 Nov. 12, 1974 [54] APPARATUS FORYFABRICATING BRUSHES 3,642,415 2 1972 Johnson 1, 425 400 X HAWNG MOLDED ENDS FOREIGN PATENTS OR APPLICATIONS lnventorl Edward Bischoff, 515 Main St, 1,111,028 10 1955 France 300/21 Old Saybrook, Conn. 06475 [22] Filed: Mar. 22, 1972 Primary Examiner-R. Spencer Annear Attorney, Agent, or FirmFlynn & Frlshauf [21] Appl. No.: 236,938

. 57 ABSTRACT- [52] US. Cl 425/500, 425/398, 425/400, A brush molding method and apparatus in which gym Int Cl B2 thetic brush filaments within a mold cavity are held in I n v t t u I U Q [58] held of Search 425/109 2 9 ends of the synthetic brush filaments are heated and 264/ 300/21 melted into a liquid mass in the mold cavity, and a 6 brush handle is then inserted into the mold cavity, [5 1 References C'ted closing the mold and pressing the liquid into the de- UNITED STATES PATENTS sired shape, and at the same time fusing the filaments 638,738 12/1899 Morris 425/805 X together to form a base for the brush and sealing the 2,397,471 4/1946 Cox 264/243 X formed base to the handle. T0 mold a brush without a 2,652,580 9/1953 Neugass 300/2] X handle a movable platen be ubstitutcd for the 2,653,056 9 1953 Montero et al.. 300/21 handle, 2,664,316 12/1953 Winslow, Jr. et al 300/21 3,200,451 8/1965 19 Claims, 11 Drawing Figures Worswick sum 10! 2 3'847'532 4 A H. B 9 A l m 2A\\\,\\\ F IVIIIIIII FIG? PAIENTEBnuv 12 I974 T I I DRIVE MEANS OR PLUG 1 F|G.2 G

PAIENTEU I 2 9 4 3. 47 5 SHEET 20F 2 4 F|G.8- Fl G. 5 HEAT APPLICATION STATION 4b STLE DING

STATION HANDLE INSERTION STATION 4c l EJECTION STATION 4d APPARATUS FOR FABRICATING BRUSHES HAVING MOLDED ENDS The present invention relates to brushes and apparatus and methods for making same. More particularly, the apparatus and method of the present invention are directed to fabricating brushes from synthetic materials, such as, for example, nylon filaments, polypropylene, polyester, and other thermoplastic and/or moldable material.

In the brush making art, use is generally made of epoxy, rubber or other solidifying adhesive materials for bonding together the filaments of the brush. When using such materials, equipment for pouring the adhesive into a partially assembled brush is required, and also, it is necessary to allow time for curing the adhesive. Further, a metal ferrule and one or more plugs are generally used to contain the filaments and hold them in the desired form. This is particularly true in the paint brush art. Generally, after formation of the bristle portion of the brush, the handle is set into the ferrule by nailing, stapling, or the like. In the broom making art, the handle is generally bound to the filaments or bristles.

Several advances have been made in the prior art 4 techniques, as exemplified by U.S. Pat. No. 3,471,202

to J. C. Lewis, Jr. This patent is related to making of tufted type brushes and is only directed to formation of a tuft from synthetic filaments and for then setting the tuft into a holding block, or the like.

The object of the present invention is to eliminate the I SUMMARY OF THE INVENTION According to a first aspect of the present invention a method for fabricating brushes includes inserting a plurality of synthetic filaments into a hollow mold which defines a cavity therein, the mold including a movable plug member located substantially centrally of the mold and which is movable in the longitudinal direction of the filaments. The movable plug in one embodiment, is located in a first position (either within the lower portion of the mold or outside the mold) during insertion of the synthetic filaments into the mold and is movable to a second position within the mold to effectively separate the mold into two cavities and to form a void space substantially centrally of the filaments. The plug may be located above the mouth of the mold to receive filaments, and then retracted into the mold to form the two cavities therein and to form the void space. Free ends of the filaments are heated to liquify same, and a platen element is inserted into the liquified material. The liquified material is solidified adjacent the platen element, and the completed brush is removed from the mold. Preferably, removal from the mold is carried out by moving the movable plug in the direction of the platen to eject same from the mold.

According to a further aspect of the present invention, apparatus for fabricating brushes includes a hollow mold defining a cavity therein, the cavity having an open end through which is received a plurality of synthetic brush filaments. A movable plug member is inserted substantially centrally of the mold, and is movable in the longitudinal direction of the filaments. The movable plug member is movable from a first position for receiving filaments in the mold, to a second position interior of the mold for engaging the filaments with the inner surface of the mold which effectively separates the mold into first and second cavity portions which are isolated from each other, and which substantially centrally separates the filaments during fabrication of the brush. The movable plug member is preferably further movable to eject the finished brush from the mold. The first position of the movable plug member may be inside the mold or exterior of the mold to receive filaments into the mold.

The plug member is preferably tapered to facilitate the passing of the filaments therearound, such as during insertion of the filaments into the mold, and during movement of the plug.

According to yet another aspect of the invention, a plurality of molds may be mounted on a support device, such as a turret, for performing steps successively to mass produce brushes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a mold and a partial sectional view of a movable plug for use in fabricating brushes in accordance with the present invention;

FIG. 2 is an end view of the mold of FIG. 1;

FIG. 3 is a sectional view of the mold of FIG. I with synthetic brush filaments inserted therein and the plug in operating position, and showing the application of heat to the exposed filaments;

FIG. 4 is a sectional view of the mold with the brush handle inserted in the melted synthetic filament material;

FIG. 5 illustrates the molded brush after removal from the mold;

FIG. 6 illustrates a ferrule for use in a modification of the present invention;

FIG. 7 is an abbreviated sectional view similar to that of FIG. 1 with the ferrule of FIG. 6 in place in the mold;

FIG. 8 is an abbreviated sectional view similar to that of FIG. 4 showing a metal movable platen instead of a brush handle for use in compression molding a brush without a handle;

FIG. 9 illustrates a brush which is compression molded without a handle using the technique and apparatus of FIG. 8;

FIG. 10 is a sectional view of an alternative filament loading arrangement of the mold and plug of the present invention; and I FIG. 11 shows a typical arrangement for mass production of brushes according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2 a movable metal positioning plug 1 is movably inserted in a mold 4 which defines a cavity 5 therein. The mold 4 is cylindrical in shape when fabricating round brushes or rectangular in shape with rounded edges when fabricating fiat brushes. The plug 1 has a pointed tip end 2 to divide and push through the mass of filaments 9 as they are inserted in the mold 4. As shown in FIG. 3, the plug 1 provides a central opening for the filaments to form a brush having excellent characteristics. The plug 1 also has a shaft or pin portion 3 which extends from the tip end 2 through the closed end of the mold 4 through aperture 8. Positioning of the plug 1 within the cavity of mold 4 is accomplished by movement of the shaft 3 in the direction of the arrows A and B. The shaft 3 and tip end 2 of plug 1 may be integral with each other or may be connected together by, for example, screw threads, adhesives, etc.

The walls of the mold 4 are fabricated of metal, rigid fiber or other rigid material. The cavity 5 within the mold 4 will be generally cylindrical in form as shown in FIG. 2 for round brushes, or oblong (not shown) for fiat brushes. Within the mold 4 there is formed a shoulder 6 to give compression to the mass of filaments 9 when the plug 1 is in the advanced (or upward) position as shown in FIG. 3. A cylindrical enlargement or trough 7 is also preferably formed in the mold cavity to permit the filament ends to deflect and pass the plug 1 when the filaments 9 are being placed in the mold with the plug retracted to its lower position as shown in FIG. 1. The mechanical means 22 for moving the shaft 1 are not shown in detail so as not to unduly obscure the present inventive concept. The tip end 2 of plug 1 is shown round in this embodiment. However, the shape thereof may be varied, depending upon the shape of the mold 4 and the shape of the brush being formed.

FIG. 3 illustrates a mass of filaments 9 positioned within the cavity of mold 4. Plug 1 is shown advanced to the molding position. The inner shoulder 6 of the mold wall engages the mass of filaments 9 pressed against it by the plug 1 to form an effective closure separating parts a and 15b of the mold cavity. Heat is directed, for example by a flame element 20, towards the exposed filaments in the open mold cavity 15b. The filament mass in cavity 150 is effectively insulated from the direct heat and molding pressure by the shoulder 6 which presses thereagainst. Sufficient heat is applied to completely liquify by melting the filament mass extending into cavity 15b. This melting may be achieved by an open flame, a jet of heated inert gas, radiation from a hot metal mass that does not touch the filaments, directed and controlled heat rays, ultrasonic waves, direct contact by a heated platen, or any other suitable heating means.

As shown in FIG. 4, the exposed filament material in cavity 15b is melted to liquifaction, and then the movable platen ltlI in the form of the brush handle is moved into the upper opening of the mold 4. Under slight pressure the melted filament material is pressed into the desired shape 11, being sealed at the same time to the handle 10 by engaging the circular indentation 12. Indentation 12 may be formed continuously on the periphery of handle 10 or may be spaced thereabout. In the molding process, after cooling, the filaments 9 are fused to each other at their heated ends and to the solidified filament material at 13, giving shape and rigid bonding to the brush components. As shown in FIG. 5, the solidified filament material at 11 provides a finished outer surface-for the brush where the filaments join the handle.

The handle 10 may be made of a material which will fuse with the molten filament material. In this event the indentations 12 can be eliminated. However, providing indentation 12 will provide a more secure structure.

The finished brush is preferably removed from the mold by pushing the pin 1 upward in the direction of arrow A to a position higher than that shown in FIG. 4 to push the finished brush out of the mold 4. Alternatively, after cooling the handle 10 can be lifted for removal, but pushing out with plug 1 creates fewer stresses in the brush and is preferable.

A brush with a separately inserted ferrule can also be fabricated. Referring to FIGS. 6 and 7, a ferrule 14, either of the same material as the filaments 9 or of other suitable materials, and having the desired color and composition, may be used. The ferrule 14 is preferably a previously fabricated circular band (FIG. 6) and is inserted in the mouth of the mold 4 (FIG. 7) prior to inserting the filaments 9 in the mold. The heat application procedure is the same as described in the foregoing example. If the ferrule 14 is of the same material as the filaments 9, fusion of the ferrule 14 to the filament material will occur. If the ferrule material is of different material, the ferrule 14 will adhere by compression of its molten surface (during the heat application) into the circular groove 12 of the handle 10. The filament material will fuse to the molten surface of the ferrule.

If it is desired to fabricate a brush having no handle, a movable metal platen 16 (FIG. 8) is substituted for the handle 10 of FIG. 4, producing a brush base 17 of contour and pattern according to the mold surface design of platen 16. Ejection of the brush is preferably by pushing same out of the mold by raising movable plug 1.

As shown in FIG. 10 alternative arrangement of the present invention is to provide the plug 1 in an extended position above the open mouth of the mold 4 during insertion of the filaments therein. In this embodiment of the invention, it is preferable to utilize a conical funnel structure 23 for aiding the insertion of the filaments into the mold around the extended plug 1. After insertion of the filaments, the plug 1 is retracted into the mold to the position shown in FIG. 3. The remainder of the operations described above are then carried out substantially without variation. An advantage of this method is that when the plug is retracted downwardly into the mold after insertion of the filaments, the plug aids in firmly seating the filaments against the bottom of the mold to provide a more consistent contour of the resulting brush.

A further advantage of the embodiment of FIG. 10 whereby the movable plug 1 is extended above the open end of the mold 4 during the insertion of filaments 9, is that the mechanism for moving the plug up and down need only be movable between two positions. It is not necessary for the movable plug to be retractable to the bottom portion of the mold, and therefore, the only two positions required are a retracted position to the position shown in FIG. 3 and an extended position shown in FIG. 10. This simplifies the operating mechanism and upon ejection of the brush, it is merely necessary to move the plug to the position shown in FIG. 10, thereby ejecting the brush and simultaneously setting up the device for receipt of the next batch of filaments.

A still further arrangement (not shown) according to the present invention includes locating the plug outside the mold in the vicinity of the end of the mold remote from the end where heat is applied. After loading of the filaments through said remote end of the mold adjacent the plug, the plug is moved interior of the mold and the remainder of the steps are carried out.

As described hereinabove, an important feature of the present invention is the movable plug '1 which serves to position the filaments 9 in the desired direc- F ther, the plug 1 eliminates .the need for fabricating separate tufts to achieve separation in the bristle mass at the brush block. No brush block, per se, is required and excellent separation of the bristles is achieved by virtue of the use of the plug 1 of the present invention.

The movable plug 1 further serves as an element in the mold cavity closure to permit compression molding and to restrict heat absorption by the lower portions of the bristles. This eliminates undesired melting of the synthetic bristles below the portion at which the heat is applied. Plug 1 effectively serves as a heat sink during the molding process.

The movable plug 1 also preferably serves as a knock-out pin to eject the finished brush from the mold after the fabrication process.

The lower surface 23 of the mold 4 is preferably concave as shown in FIGS. 1, 3 and 4. This surface 23 locates the filaments so that the work end of the resulting brush has the proper shape or contour. The particular shape of the bottom surface 23 depends upon the desired characteristics of the brushes being fabricated. The mold 4 may be made from plural parts with a removable bottom section so that the contour of surface 23 of the bottom section can be easily and economically changed, as desired.

The mold 4 defines a cavity which is divided into two sections by positioning of the movable plug after insertion of the filaments'9. The section a contains the mass of filaments which form the body of the brush, the movable plug 1 and mold 4 combining to effectively insulate the lower portions of the filaments from direct heat and molding pressure. Section 15b is an open mold cavity during heat application, and becomes a closed pressure mold on insertion of the handle as a movable pla ten. The mold 4 is designed such that the heat is effecgively guided to the desired portions of the filaln er'its, and such that a ferrule can optionally be used with the present invention. The mold may have straight inside walls (i.e. shoulder 6 may be eliminated), but far better results are obtainable using the shoulder 6 to provide more distinct sections 15a and 15b to facilitate filament loading and to provide better heat isolation between cavities. Further, it is possible to use the mold of the present invention with a cold mold compression technique to give shape to the molten filament ends, after melting thereof.

Further, in accordance with the present invention, a plurality of mold 4 and movable plug 1 combinations can be mounted on a movable platform, such as a turret, to provide an effective mass-production of brushes. As shown in FIG. 11, a turret 24 is advanceable (i.e.,

' rotatable) in the direction of the Arrow D (by means not shown) to position molds 4a-4d to various fabrication stations. For example, at 4a, filaments 9 are inserted into the mold 4 with the movable plug 1 in its lower-most position as illustrated in FIG. 1. The position of FIG. 10 may also be used. The details of the insertion of filaments are not shown in FIG. 11 forthe sake of clarity. While filaments are being loaded into mold 4a, heat is applied to the previously loaded filaments in mold 4b at the heat application station. After heating, the handle 10, or the like can be inserted at the heat application station, or the turret could be advanced to locate the mold at a handle insertion station (shown in FIG. 11) for insertion of the handle into the molten material. As mentioned above, a separate handle insertion station could be eliminated and the handle could be inserted at the heat application station. At the ejection station, the completed brush is ejected preferably by. raising the movable plug 1, as discussed hereinabove. As should be apparent to one skilled in the art, the mechanisms for moving the plug 1, for inserting the filaments and handle, and for applying the heat, are not shown. Also, the advancing mechanism for the turret 21 is not shown. The implementation of the various mechanisms to carry out these functions should be apparent in view of the state of the art. Further, it is not necessary that the molds be located on a rotatable turret as shown in FIG. 11. Any other convenient advancing mechanism for advancing the molds from station to station can be used. Alternatively, the molds could be stationary and the various operating mechanisms for applying heat, loading filaments, etc., can be movable relative to the fixed molds.

It should be clear that the molds in the present inven-' tion could be located in any orientation during use. However, care should be taken that the liquified filament material is now allowed to run out of the mold. The vertical orientation was shown in the figures merely by way of example and does not limit the scope of the invention. For example, when a hot platen is used to liquify the filaments, such as shown in FIG. 8, for example, the mold could be inverted and lowered into hot platen. Various other modifications should be apparent.

. It should be clear that before ejection of the brush from the mold, the molten material must be cooled. Various types of cooling devices, such as a blast of cool air, could be used to hasten the cooling.

While the invention has been described above with respect to specific examples, it should be clear that var ious modifications and alterations could be made within the spirit of the present invention as defined by the appended claims.

I claim:

1. Apparatus for fabricating brushes comprising:

a hollow mold defining a cavity therein, said cavity being adapted to receive a plurality of synthetic brush filaments through anopen end thereof;

a movable plug member movably inserted substantially longitudinally centrally of said mold, and movable in the longitudinal direction of said filaments; and

means for moving said movable plug member from a first position relative to said cavity for receiving filaments in said mold cavity, to a second position interior of said mold cavity for engaging said filaments with an inner surface of said mold, said filaments received in said mold being of sufficient number and said mold and said plug member being so dimensioned as to tightly press said filaments between said inner surface of said mold and said plug member which effectively separates said mold into first and second inner cavity portions which are isolated from each other and which substantially centrally separates said filaments during fabrication of said brush to form a space void of filaments substantially centrally of the resulting brush, said movable plug member by said tightly pressing said filaments between itself and said inner surface of said mold substantially preventing flow of molten filament material between adjacent pressed portions of said filaments and shielding portions of said filaments in said mold cavity from heat applied to the filament ends in an end portion of said mold cavity.

2. Apparatus according to claim 1, wherein said first position of said movable plug is interior of said mold and remote from said open end of said mold.

3. Apparatus according to claim 1, wherein said first position of said movable plug is exterior of said mold.

4. Apparatus according to claim 3, wherein said first position of said plug is adjacent the open end of said mold.

5. Apparatus according to claim 1, including a funnel member. received in said open end of said mold for guiding filaments into said mold.

6. Apparatus according to claim 1, wherein said hollow mold has an inwardly projecting shoulder at an intermediate portion thereof to define a pair of cavities in said mold, said movable plug member being movable to said second position to engage said filaments with said shoulder, thereby effectively isolating said mold into said cavities.

7. Apparatus according to claim 1, wherein said moving means moves said movable plug to a position toward said open end of said mold to eject a finished brush from said mold.

8. Apparatus according to claim 1, wherein said moving means includes an extension of said plug extending out from the bottom of said mold.

9. Apparatus according to claim 1, wherein the endmost free end of said plug member is tapered to facilitate passing of said filaments therearound during insertion of said filaments into said mold, and to facilitate moving said plug to said second position.

10. Apparatus according to claim 4, wherein said plug member is tapered to facilitate retracting of same into said mold to said second position.

12. Apparatus according to claim 1, wherein said mold has a bottom surface of predetermined curvature to shape the end of the resulting brush.

13. Apparatus according to claim 1, including heat ing means for heating the ends of said filaments to liquify same.

14. Apparatus according to claim 1 comprising a rotatable turret means which is adapted to receive a plurality of said molds, said turret means including means for rotating said turret to successively move said plurality of molds to respective operating stations.

15. Apparatus according to claim 14 wherein said operating stations comprise respective stations for inserting filaments, heating filaments and ejecting brushes from said mold.

16. Apparatus for fabricating brushes comprising:

a hollow mold having an inwardly projecting shoulder at an intermediate portion thereof to define a pair of cavities therein, said cavities being adapted to receive a plurality of synthetic brush filaments through an open end thereof;

a movable plug member movably inserted substantially longitudinally centrally of said mold, and movable in the longitudinal direction of said filaments; and

means for moving said movable plug member from a first position relative to said cavity for receiving filaments in said mold cavity, to a second position interior of said mold cavity for engaging said filaments with said shoulder of said mold to effectively separate said mold into first and second inner cavities and to separate said filaments during fabrication of said brush, said movable plug member further shielding portions of said filaments in said mold cavity from heat applied to the filament ends in an end portion of said mold cavity.

17. Apparatus according to claim 1 wherein said movable plug member has a tapered portion which tapers inwardly relative to the inner surface of said mold, the widest portion of said plug member tightly pressing said filaments against said inner surface of said mold.

18. Apparatus according to claim 16 wherein said movable plug member separates said mold into first and second inner cavities which are isolated from each other.

19. Apparatus according to claim 16 wherein said movable plug member, by said tightly pressing said filaments between itself and said inner surface of said mold, substantially prevents flow of molten filament material between adjacent pressed portions of said fila- 

1. Apparatus for fabricating brushes comprising: a hollow mold defining a cavity therein, said cavity being adapted to receive a plurality of synthetic brush filaments through an open end thereof; a movable plug member movably inserted substantially longitudinally centrally of said mold, and movable in the longitudinal direction of said filaments; and means for moving said movable plug member from a first position relative to said cavity for receiving filaments in said mold cavity, to a second position interior of said mold cavity for engaging said filaments with an inner surface of said mold, said filaments received in said mold being of sufficient number and said mold and said plug member being so dimensioned as to tightly press said filaments between said inner surface of said mold and said plug member which effectively separates said mold into first and second inner cavity portions which are isolated from each other and which substantially centrally separates said filaments during fabrication of said brush to form a space void of filaments substantially centrally of the resulting brush, said movable plug member by said tightly pressing said filaments between itself and said inner surface of said mold substantially preventing flow of molten filament material between adjacent pressed portions of said filaments and shielding portions of said filaments in said mold cavity from heat applied to the filament ends in an end portion of said mold cavity.
 2. Apparatus according to claim 1, wherein said first position of said movable plug is interior of said mold and remote from said open end of said mold.
 3. Apparatus according to claim 1, wherein said first position of said movable plug is exterior of said mold.
 4. Apparatus according to claim 3, wherein said first position of said plug is adjacent the open end of said mold.
 5. Apparatus according to claim 1, including a funnel member received in said open end of said mold for guiding filaments into said mold.
 6. Apparatus according to claim 1, wherein said hollow mold has an inwardly projecting shoulder at an intermediate portion thereof to define a pair of cavities in said mold, said movable plug member being movable to said second position to engage said filaments with said shoulder, thereby effectively isolating said mold into said cavities.
 7. Apparatus according to claim 1, wherein said moving means moves said movable plug to a position toward said open end of said mold to eject a finished brush from said mold.
 8. Apparatus according to claim 1, wherein said moving means includes an extension of said plug extending out from the bottom of said mold.
 9. Apparatus according to claim 1, wherein the endmost free end of said plug member is tapered to facilitate passing of said filaments therearound during insertion of said filaments into said mold, and to facilitate moving said plug to said second position.
 10. Apparatus according to claim 4, wherein said plug member is tapered to facilitate retracting of same into said mold to said second position.
 11. Apparatus according to claim 10, wherein the endmost free end of said plug member is tapered to facilitate passing of said filaments therearound during insertion of said filaments into said mold.
 12. Apparatus according to claim 1, wherein said mold has a bottom surface of predetermined curvature to shape the end of the resulting brush.
 13. Apparatus according to claim 1, including heating means for heating the ends of said filaments to liquify same.
 14. Apparatus according to claim 1 comprising a rotatable turret means which is adapted to receive a plurality of said molds, said turret means including means for rotating said turret to successively move said plurality of molds to respective operating stations.
 15. Apparatus according to claim 14 wherein said operating stations comprise respective stations for inserting filaments, heating filaments and ejecting brushes from said mold.
 16. Apparatus for fabricating brushes comprising: a hollow mold having an inwardly projecting shoulder at an intermediate portion thereof to define a pair of cavities therein, said cavities being adapted to receive a plurality of synthetic brush filaments through an open end thereof; a movable plug member movably inserted substantially longitudinally centrally of said mold, and movable in the longitudinal direction of said filaments; and means for moving said movable plug member from a first position relative to said cavity for receiving filaments in said mold cavity, to a second position interior of said mold cavity for engaging said filaments with said shoulder of said mold to effectively separate said mold into first and second inner cavities and to separate said filaments during fabrication of said brush, said movable plug member further shielding portions of said filaments in said mold cavity from heat applied to the filament ends in an end portion of said mold cavity.
 17. Apparatus according to claim 1 wherein said movable plug member has a tapered portion which tapers inwardly relative to the inner surface of said mold, the widest portion of said plug member tightly pressing said filaments against said inner surface of said mold.
 18. Apparatus according to claim 16 wherein said movable plug member separates said mold into first and second inner cavities which are isolated from each other.
 19. Apparatus according to claim 16 wherein said movable plug member, by said tightly pressing said filaments between itself and said inner surface of said mold, substantially prevents flow of molten filament material between adjacent pressed portions of said filaments. 